The invention relates generally to cardiac rhythm management systems, and particularly, but not by way of limitation, to a system providing, among other things, reversionary behavior in multi-chamber pacing therapy.
When functioning properly, the human heart maintains its own intrinsic rhythm, and is capable of pumping adequate blood throughout the body""s circulatory system. However, some people have irregular cardiac rhythms, referred to as cardiac arrhythmias. Such arrhythmias result in diminished blood circulation. One mode of treating cardiac arrhythmias includes the use of a cardiac rhythm management system. Such systems are often implanted in the patient and deliver therapy to the heart.
Cardiac rhythm management systems include, among other things, pacemakers, also referred to as pacers. Pacers deliver timed sequences of low energy electrical stimuli, called pace pulses, to the heart, such as via an intravascular lead (referred to as a xe2x80x9cleadxe2x80x9d) having one or more electrodes disposed in or about the heart. Heart contractions are initiated in response to such pace pulses (this is referred to as xe2x80x9ccapturingxe2x80x9d the heart). By properly timing the delivery of pace pulses, the heart can be induced to contract in proper rhythm, greatly improving its efficiency as a pump. Pacers are often used to treat patients with bradyarrhythmias, that is, hearts that beat too slowly, or irregularly.
Cardiac rhythm management systems also include cardioverters or defibrillators that are capable of delivering higher energy electrical stimuli to the heart. Defibrillators are often used to treat patients with tachyarrhythmias, that is, hearts that beat too quickly. Such too-fast heart rhythms also cause diminished blood circulation because the heart isn""t allowed sufficient time to fill with blood before contracting to expel the blood. Such pumping by the heart is inefficient. A defibrillator is capable of delivering a high energy electrical stimulus that is sometimes referred to as a defibrillation countershock. The countershock interrupts the tachyarrhythmia, allowing the heart to reestablish a normal rhythm for the efficient pumping of blood. In addition to pacers, cardiac rhythm management systems also include, among other things, pacer/defibrillators that combine the functions of pacers and defibrillators, drug delivery devices, and any other implantable or external systems or devices for diagnosing or treating cardiac arrhythmias.
One problem faced by cardiac rhythm management systems is the treatment of congestive heart failure (also referred to as xe2x80x9cCHFxe2x80x9d). In some forms, congestive heart failure can be treated by biventricular coordination therapy that provides pacing pulses to both right and left ventricles, by biatrial coordination therapy that provides pacing pulses to both the right and left atrium, or other multichamber coordination therapy. Biventricular and biatrial coordination therapy each rely on multiple leads and multielectrode leads to carry out the coordination therapy of multiple chambers of the heart. In the event of a failure in one or more of these leads, or their associated circuity, the ability to perform coordination therapy is generally lost.
As will be seen from the above concerns, there exists a need for improved failure recovery mechanisms in cardiac rhythm management systems used in biventricular and/or biatrial coordination therapy. The above-mentioned problems with failure recovery and other problems are addressed by the various embodiments of the invention and will be understood by reading and studying the following specification.
The various embodiments of the invention include methods for failure recovery in a cardiac rhythm management system and apparatus capable of carrying out the methods. The methods include applying a first pacing therapy using one or more leads and/or electrodes. The methods further include detecting a failure condition on one or more of the leads and/or electrodes, wherein the failure condition prohibits or frustrates application of the first pacing therapy. The methods still further include subsequently applying a second pacing therapy using a new combination of one or more of the leads and/or electrodes. The second pacing therapy is preferably chosen such that the detected failure does not interfere with the second pacing therapy. The second pacing therapy may be applied for only one cardiac cycle. The second pacing therapy may further be applied continuously until the failure condition is resolved, or it may be latched such that physician intervention is required to resume the first pacing therapy.
One embodiment includes a method of delivering pacing therapy to a heart. The method includes delivering a first therapy to a first and second electrode coupled to the heart, detecting a failure associated with the first electrode, discontinuing the first therapy during a period of the failure associated with the first electrode, and delivering a second therapy to the second electrode during the period of the failure associated with the first electrode.
Another embodiment includes a method of delivering pacing therapy to a heart. The method includes delivering a first therapy to a first and second electrode of a lead adapted for implantation on or about the heart. The lead includes a main lead body adapted to carry signals to and from the heart, a first electrode associated with the main lead body, and a second electrode associated with the main lead body. The first and second electrodes are routed through the coronary sinus upon implantation. The method further includes detecting a failure associated with the first electrode, discontinuing the first therapy during a period of the failure associated with the first electrode, and delivering a second therapy to the second electrode during the period of the failure associated with the first electrode.
A further embodiment includes a cardiac rhythm management system. The system includes a first electrode adapted to couple to a first chamber of a heart, a second electrode adapted to couple to a second chamber of the heart, a signal generator for producing pulses to apply to the heart, wherein the signal generator is coupled to the first electrode and the second electrode for applying the pulses, and a processor coupled to the signal generator. The processor is adapted to cause the signal generator to deliver a first therapy to the first electrode in the absence of a failure detection associated with the first electrode, and to deliver a second therapy to the second electrode in the presence of a failure detection associated with the first electrode.
A still further embodiment includes a cardiac rhythm management system. The system includes a signal generator for producing pulses to apply to the heart and a lead adapted for implantation on or about the heart and for connection to the signal generator, wherein the lead includes a main lead body adapted to carry signals to and from the heart, a first electrode associated with the main lead body and a second electrode associated with the main lead body, the first and second electrodes being routed through the coronary sinus upon implantation. The system further includes a processor coupled to the signal generator, wherein the processor is adapted to cause the signal generator to deliver a first therapy to at least the first electrode in the absence of a failure associated with the first electrode, and to deliver a second therapy to the second electrode in the presence of a failure associated with the first electrode.
An additional embodiment of the cardiac rhythm management system includes both a first and a second lead, where both leads have at least one electrode to sense cardiac signals and to deliver pulses to the heart. The system further includes a processor coupled to a signal generator, were the signal generator produces pulses to apply through the electrode(s) on the first and second leads. The processor is adapted to cause the signal generator to deliver a first therapy through the at least one electrode of the first lead and to deliver a second therapy through the at least one electrode of the second lead in the presence of a failure detection associated with the first lead.
Other embodiments include methods and apparatus of varying scope.